Railway signaling system.



L. H. THULLEN.

RAILWAY SIGNALING SYSTEM.

APPLICATION FILED MAY 16, 1904. 1,030,436, Patented June 25, 1912.

2 SHEETS-SHEET 1.

WITNESSES: Y INVENTOR CZ W MM I A I 46,11 ATTORNE COLUMBIA PMNOCIRAPHCO.,WASNXNO1'ON. D. c.

L. H. THULLEN. RAILWAY SIGNALING SYSTEM.

APPLICATION IILED MAY 16, 1904.

1,030,436, Patented June25, 1912.

2 SHEETS-SHEET 2.

WITNESSES: v INVENTOR a 1 W I Dfuo' *A J/u ATTORNEY COLUMBIA PLANOCIRAPHcon WAsmNu'roN. B. c.

urn STATES PATENT OFFICE.

LOUIS HENRY TI-IULLEN, OF EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO THE.UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORA-TION OF PENNSYLVANIA.

RAILWAY SIGNALING SYSTEM;

Specification of Letters Patent.

Patented June 25, 1912.

To all whom it may concern:

Be it known that I, LOUIS I-I. THULLEN, a citizen of the United States,residing at Edgewood Park, in the county of Allegheny and State ofPennsylvania, have in.

' cuits) to actuate railway signals, the two currents being different incharacter, pref erably as regards frequency.

I employ both track rails as a return for the alternating propulsioncurrent, and both rails as conductors for the signaling current of thetrack circuits, and I employ signal controlling devices which willrespond to the signal current to close a local or signaling circuit butremain unresponsive to the propulsion current.

Several ways in which I accomplish the objects just stated are disclosedin the drawings, in which Figure 1 is a diagrammatic view showing asignaling system embodying my invention. Figs. 2, 3, and 4 are viewsshowing modifications of the system shown in Fig. 1.

Referring to Figs. 1 and 2,-1 and 2 designate the parallel lines ofrails of a trackway. Each line of rails is divided by insulation to formsections which I shall hereinafter refer to as block sections. 1

have shown three such block sections, 3, 4 and 5. At the ends of eachblock section and near the insulation points, I locate inductive orreactance bonds which I have designated 6, 7, 8 and 9. The windings ofthe reaotance bonds are connected with the opposite rails of their blocksection, and the middle points of the windings of adjacent bonds in twoadjacent block sections are joined by suitable conductors; 10 and 11designate two such conductors. This arrangement is clearly set forth inmy applications filed February 5, 1904, Serial Nos. 192,145 and 192,146.The form of bond employed may be that set forth in my United StatesLetters Patent No. 838,916 granted Dec. 18, 1906.

12 designates a generator of alternating propulsion current, which maybe of any type suitable for the purposes hereinafter stated. Oneterminal of the generator 12 is connected with the track rails; forexample to the middle point of the winding of an inductive bond 13bridged across the rails of a block sect-ion as shown in block section5. The other terminal of the generator 12 is connected with a trolleywire or third rail 14 through which motive power current is conducted toa trolley 15, trolley pole 16, and a motor (not shown) of a railwayvehicle 17 conventionally indicated by a pair of wheels and an axle onthe rails 1 and 2. The circuit for the propulsion current from thegenerator 12 through a car motor and back to the generator may be tracedas follows: from generator 12 through wire 14, trolley 15, trolley pole16, motor of car 17, rails of section 3, winding of bond 6, wire 10,winding of bond 7, rails of section 4, winding of bond 8, wire 11,winding of bond 9, rails of section 5, winding of bond 13 to generator12.

The resistance of the two lines of rails being substantially equal, thealternating propulsion current will normally divide itself equallybetween them; but any one qual distribution of current between the railswill cause an unbalancing of the current in the windings of theinductive bonds 6, 7, 8 and 9. The propulsion current traverses bothlines of rails in the same direction; but the adjacent bonds having thecenters of their windings connected together, the current from one railtraverses one half of each Winding in one direction and the current fromthe other rail traverses the other half of the winding in the oppositedirection, whereby the currents in the two halves of the windingsneutralize each other in their magnetizing action on the cores of thesaid bonds. The cores are, therefore, unaffected by the propulsioncurrent, provided it be equal in each line of rails, and the voltageacross the terminals of the bonds 6, 7, 8 and 9 is zero. If, however,the propulsion current be unequal in I the two lines of rails of a blocksection, a counter electro-motive force due to the unbalancing of thecurrent would be set up in the inductive bonds of that block section,

and a difference of potential of propulsion connected with that blocksection if the relay were constructed to respond to current of thefrequency of the propulsion current. This relay must not, therefore, beoperative by any difference of potential of the propulsion currentacross the rails of the block sections.

18 designates a generator of alternating signaling current differing incharacter from the current generated by the generator 12, the diflerencebeing preferably in frequency. The terminals of the generator 18 areconnected with mains 19 and 20. For each block section I provide atransformer, 21 having its primary winding connected with the mains 19and 20, and its secondary winding connected with the rails of the blocksection.

The current from transformer 21 of each block section traverses thewindings of the bonds 6, 7, 8 and 9 in one direction, and the bonds aretherefore inductive to such current.

For each block section I provide a relay 23 which is adapted to close alocal circuitthat is to say, it closes the local circuit when energizedby alternating current intended for its operation, and opens the localcircuit when the alternating signaling current is shunted from it andalso when the relay is improperly energized by the alternatingpropulsion current. I therefore provide means at some point in eachtrack circuit which acts to prevent the alternating propulsion currentfrom improperly energizing the relay to cause itto close the localcircuit when the local circuit should be open. Referring now to Fig. 1,one lead 25 to the relay 23 is divided into two branches 26 and 27, theformer branch including a condenser 28 and the latter an inductivewinding 29. In Fig. 2, the lead 25 to the relay.

23 is branched in the same manner, but in this case each of the brancheshas acondenser 28 and 30, having different sizes or values, and eachbranch also has an impedance or inductive winding 31 and 32,

. center and the other winding on the other side of the center thereof.A connecting wire between the, two windings 33 and 34 than the other and.will actuate the armature to close the local or signaling circuit,while if car propulsion current traverses the divided circuit theenergization of the two windings will be equal and opposite, and theywill, therefore, have no rotative effecton the relay armature.

In the system embodying my invention, the propulsion current has onefrequency, and the signaling current a different frequency. For example,the frequency of the propulsion current might be twenty-five cycles persecond, and that of the signaling current sixty cycles per second.

In the system shown in Fig. 1, the condenser 28 and the inductivewinding 29 are so proportioned that current of the frequercy of thepropulsion current traverses both equally, that is, the current throughthem varies equally as the difference of potential varies. Hence anychange in the potential of the propulsion current across the terminalsof the inductive bonds, and therefore across the terminals of the relay,will not unbalance the currents in the branches 26 and 27, and theaction of the windings 33 and 34 on the armature remains balanced. Butif the apparatus is thus proportioned for equal currents through the twowindings 33 and 34 at one frequency, the currents in these two windingswill be unbalanced at any other frequency. This is for the reason thatthe current through a condenser increases in proportion to the frequencyat a given voltage, while under the same condition the current throughan inductive circuit decreases. If, therefore, a current of a frequencyhigher than that of the propulsion current be impressed on the terminalsof the relay, the current in the branch 26 which includes the condenser28, will increase, while that in the branch 27 which includes theimpedance 29 will decrease. The currents in the windings 33 and 34 beingtherefore unbalanced, the armature will be operated to close the localcircuit for the signal 38.

In the system shown in Fig. 2, the condensers 28 and 30 and theimpedances 31 and 32 are so proportioned that, as described for thepreceding system, at one frequency, preferably at the frequency of thepropulsion current, the currents in the two branches 26 and 27 are equaland the relay contact is free to open. At a higher frequency, however,the balance is destroyed and the relay is operated to close the localcircuit for signal 38.

Referring now to Figs. 3 and 4, I have here shown systems similar tothose of Figs. 1 and 2, except that in each of the branches 26 and 27 ofthe relay circuit is included a primary winding 41 of a transformer 40,these windings being in the same direction for each branch. A relay 42has a single controlling winding 43 which is connected with a secondarywinding 44 of the transformer 40. In Fig. 3, the branches 26 and 27include, respectively, a condenser 28 and an impedance 29 which areadjusted to balance at the propulsion current frequency as heretoforedescribed for the system shown in Fig. 1. As long as the currents inboth primary windings of the transformer 40 are equal there will be nocurrent induced in the secondary winding 44; but a current of a higherfrequency will unbalance the currents in the two primary windings 41 andwill therefore cause a current to be induced in the secondary winding 44which Will operate the relay 42 to close its local or signaling circuit.The system of Fig. 4 is similar to that of Fig. 3, except that thecondenser 28 and the impedance 29 are included in one branch as 26, andare so adjusted that currents in the two branches 26 and 27 are balancedat propulsion current frequency but are unbalanced at another frequency.

Referring to all of the figures, when a train enters any block in whichthere is no other train, the wheels and axles thereof shunt the signalcontrolling devices in an obvious manner, causing the local circuit tobe opened and the signal to be thrown to indicate danger. As soon as thetrain has left the block, the current will at once be restored to thesignal controlling devices, whereupon the local circuit will be closedand the signal operated to indicate a clear track.

I do not desire to limit myself to the particular appa 'atus describedand illustrated herein, as the same may be varied while still retainingthe spirit of my invention, which is the safe-guarding of the relayagainst the effects of the propulsion current, and the means forsafe-guarding may be located either in the relay or at some other pointin the track circuit.

Having thus described my invention, I claim:

1. In a signaling system for an electric railway the trackway of whichis included in the circuit for the propulsion current, a source ofalternating propulsion current, a

track circuit, a source of alternating signaling current connected withsaid track circuit and dlfli'ering in character from the propulsioncurrent, a relay having two windings each of which is connected with thetrack circuit, and means included in the circuits of the said windingsfor balancing the flow of propulsion current and for unbalancing theflow of signaling current in the two windings.

2. In a signaling system for an electric railway the trackway of whichis included in the circuit for the propulsion current, a plurality ofblock sections formed by insulations in the rails of the trackway, asource of alternating propulsion current, means connecting the blocksections for permitting the passage thereover of the propulsion current,a track circuit for each block section, a source of alternatingsignaling current con nected with each track circuit and differing incharacter from the propulsion current, a relay for each track circuithaving two windings each of which is connected with the track circuit,and means included in the circuits of the said windings for balancingthe flow of propulsion current and for 1111- balancing the flow ofsignaling current in the two windings.

8. In a signaling system for an electric railway the trackway of whichis included in the circuit for the propulsion current, a source ofalternating propulsion current, a track circuit, a source of alternatingsignaling current connected with said track circuit and differing infrequency from the pro pulsion. current, a relay having two windings,each of which windings is connected with the track circuit, and meanscomprising inductance and capacity included in circuit with the saidwindings for balancing the flow of current of the propulsion frequencyand for unbalancing the flow of current of the signaling frequency inthe two. windings.

4. In a signaling system for an electric railway the trackway of whichis included in the circuit of the propulsion current, a source ofalternating propulsion current, a source of alternating signalingcurrent differing in frequency from the propulsion current, a trackcircuit, a transformer having its primary connected with the source ofsignaling current and its secondary with the rails of the track circuit,a relay having two windings, each of which is connected with the trackcircuit, and means comprising inductance and capacity included incircuit with the said windings for balancing the flow of current of thepropulsion frequency and for unbalancing the flow of current of thesignaling frequency in the two windings.

5. In a signaling system for an electric railway the trackway of whichis included in the circuit of the propulsion current, a source ofalternating propulsion current, 'a source of alternating signalingcurrent differing in frequency from the propulsion current, a trackcircuit, a transformer having its primary connected with the source ofsignaling current and its secondary with the rails of the track circuit,a relay having two windings each of which is connected with the trackcircuit, and means comprising inductance and capacity interposed betweenthe said windings and the track circuit for 10 balancing the flow ofcurrent of the propulsion frequency and for unbalancing the flow of thecurrent of the signaling frequency of the two windings.

6. In a signaling system for an electric railway the trackway of whichis included in the circuit of the propulsion current, a plurality ofblock sections formed by insulations in the rails of the trackway,asource of alternating propulsion current, means connecting the blocksections for permitting the passage of the propulsion current thereover,a source-of alternating signaling current differing in frequency fromthe propulsion current, a track circuit for each block section, atransformer for each "track circuit having its primary connected withthe source of signaling current and its secondary with the rails of thetrack circuit, a relay for each track circuit having two windings, eachof which windings is connected with the track circuit, and meanscomprising inductance and capacity included in circuit with the saidwindings for balancing the flow of current of the propulsion frequencyand for unbalancing the flow of current of the signaling frequency inthe two windings.

7. In a signaling system for an electric railway the trackway of whichis included in the circuit of the propulsion current, a source ofalternating propulsion current, a track circuit, a source of alternatingsignaling current connected with said track circuit and differing infrequency from the propulsion current, a relay having two windings eachof which is connected with the track circuit, and means comprisinginductance and capacity included in the circuits of said windings and soproportioned that the energy in the two windings will vary. equally uponvariations of voltage of the propulsion frequency, but unequally uponvariations of voltage of the signaling frequency.

8. In a signaling system for an electric railway the trackway of whichis included in the circuit of the propulsion current,

sources of alternating propulsion and signaling currents differing infrequency, a track circuit connected with the source of signalingcurrent, a signal for said track circuit, a relay for the control ofsaid signal and comprising two windings each of which is connected withthe track circuit, inductance and capacity included in the circuits withsaid windings and so proportioned that the flow of current of thepropulsion fre- 'quency will be equal and the flow of current of thesignaling frequency will be unequal in the two windings. I

9. In a signaling system for an electric railway the trackway of which"is included in the circuit for the propulsioncurrent, a plurality ofblock sections formed by insulations in the rails of the trackway, asource of alternating propulsion current, means connecting the blocksections for permitting the passage thereover of the propulsion current,a signal for each block section, a track circuit for each block section,a source of alternating signaling current connected with each trackcircuit and differing in frequency from the propulsion current, a relayfor the control of each signal and comprising two windings each of whichis connected with the corresponding track circuit, and means comprisinginductance and capacity included in circuit with the said windings forbalancing the flow of current of the propulsion frequency and forunbalancing the flow of current of the signaling frequency in the twowindings.

10. In a signaling system for an electric railway the t-rackway of whichis included in the circuit for the propulsion current, a source ofalternating propulsion current, a track circuit, a source of alternatingsignaling current connected with said track circuit and differing infrequency from the propulsion current, a relay comprising a movablemember and two windings which windings are connected with the trackcircuit, and means comprising inductance and capacity included in thecircuits of said windings for balancing the effect on the movable memberof propulsion current in the windings, and for unbalancing the effect onthe movable member of signaling current in the wind ings.

11. In a signaling system for electric railways the track rails of whichare included in the circuit for the propulsion current, a source ofalternating propulsion current, a track circuit, a source of alternatingsignaling current connected with said track circuit and differing infrequency from the propulsion current, a relay comprising a movablemember and two windings, which windings are connected with the trackcircuit, and means comprising inductance and capacity in the circuits ofsaid windings for balancing the flow of propulsion current and.

cuit and differing in frequency from the propulsion current, a relaycomprising a movable member and two windings, which windings areconnected with the track circuit and are arranged to tend to move themovable member in opposite directions, and means comprising inductanceand capacity included in the circuits of said windings for balancing theflow of propulsion current and for unbalancing the flow of signalingcurrent in the said windings.

13. In a signaling system for electric railways the track rails of whichare included in the circuit for the propulsion current, a source ofalternating propulsion current, a track circuit, a source of alternatingsignaling current connected with said track circuit and difiering infrequency from the propulsion current, a relay comprising a movablemember of non-magnetic electro-conductive material and two windings,which windings are connected with the track circuit and are arranged totend to move the movable member in opposite directions, and meanscomprising inductance and capacity included in the circuits of the saidwindings for balancing the flow of propulsion current and forunbalancing the flow of signaling current in the said windings.

Signed at Pittsburgh this 7th day of May, 30

LOUIS HENRY THULLFN.

Witnesses M. A. BUSHMAN,

F. N. BARBER.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, I). 0"

